This disclosure relates generally to methods and apparatus for drilling a wellbore. More specifically, this disclosure relates to methods and apparatus for removing an unexpanded shoe, or other restriction, from a cased wellbore.
In the oil and gas industry, expandable tubing is often used for casing, liners and the like. To create a casing, for example, a tubular member is installed in a wellbore and subsequently expanded by displacing an expansion cone through the tubular member. The expansion cone may be pushed or pulled using mechanical means, such as by a support tubular coupled thereto, or driven by hydraulic pressure. As the expansion cone is displaced axially within the tubular member, the expansion cone imparts radial force to the inner surface of the tubular member. In response to the radial force, the tubular member plastically deforms, thereby permanently increasing both its inner and outer diameters. In other words, the tubular member expands radially.
Expandable tubulars often include a shoe assembly coupled to the lower end of the tubular that enables cementing operations to be performed through the expandable tubular. Once the expandable tubular is installed, the shoe assembly has to be removed to allow drilling to continue. This is often accomplished by milling or drilling out the shoe assembly. The shoe assembly may be constructed from composite materials, cast iron, or other materials that simplify the removal of the shoe assembly.
In certain expandable tubular applications, a portion of the expandable tubular adjacent to the shoe assembly is left unexpanded while the tubular above that portion is expanded. The unexpanded tubular creates a diametrical constriction that must also be removed before drilling ahead. Removing both the unexpanded tubular material and the shoe assembly has conventionally involved multiple trips into the wellbore for milling and fishing or the utilization of complex tools that may be prone to malfunction.
Thus, there is a continuing need in the art for methods and apparatus for removing a shoe assembly and unexpanded tubular from an expanded tubular member.